What are the diagnostic criteria for cardiogenic shock?

Diagnostic Criteria for Cardiogenic Shock

Cardiogenic shock is diagnosed when both clinical and hemodynamic criteria are met, including sustained hypotension with evidence of end-organ hypoperfusion despite adequate intravascular volume. 1

Clinical Criteria

The diagnosis of cardiogenic shock requires meeting both systolic blood pressure and hypoperfusion criteria:

Blood Pressure Criteria (one of the following):

• SBP <90 mm Hg for >30 minutes
• Mean BP <60 mm Hg for >30 minutes
• Requirement of vasopressors to maintain SBP ≥90 mm Hg or mean BP ≥60 mm Hg 1

Hypoperfusion Criteria (one or more of the following):

• Decreased mentation
• Cold extremities, livedo reticularis
• Urine output <30 mL/h
• Lactate >2 mmol/L 1

Hemodynamic Criteria

When invasive hemodynamic monitoring is available, the following parameters support the diagnosis:

• Cardiac index <2.2 L/min/m² (or <2.0 L/min/m² in some definitions)
• Pulmonary capillary wedge pressure >15 mm Hg 1

Additional Hemodynamic Parameters:

• Cardiac power output ([CO × MAP]/451) <0.6 W
• Shock index (HR/systolic BP) >1.0
• For RV shock:
  • Pulmonary artery pulse index [(PASP-PADP)/CVP] <1.0
  • CVP >15 mm Hg
  • CVP-PCW >0.6 1

Severity Classification (SCAI)

The Society for Cardiovascular Angiography and Interventions (SCAI) classification system provides a standardized approach to categorizing cardiogenic shock severity:

Stage A: At Risk

• Normal venous pressure, normotensive
• Clear lungs, normal perfusion
• Warm extremities, strong palpable pulses
• Normal mentation
• Normal renal function and lactate
• SBP >100 mm Hg with normal hemodynamics 1

Stage B: Beginning Shock ("Pre-shock")

• Elevated venous pressure
• Hypotension but normal perfusion
• Warm extremities, strong pulses
• Normal mentation
• Preserved renal function, normal lactate
• Elevated BNP
• SBP <90 mm Hg or MAP <60 mm Hg
• HR >100 bpm
• CI ≥2.2 L/min/m² 1

Stage C: Classic Cardiogenic Shock

• Elevated venous pressure
• Hypotension
• Hypoperfusion (cold, ashen, livedo)
• Weak or nonpalpable pulses
• Altered mentation
• Decreased urine output
• Respiratory distress
• Impaired renal function
• Increased lactate and BNP
• Increased liver enzymes
• SBP <90 mm Hg despite drugs and temporary MCS
• HR >100 bpm
• CI <2.2 L/min/m²
• PCW >15 mm Hg
• CPO <0.6 W 1

Stage D: Deteriorating

• Same as stage C but with worsening hypotension and hypoperfusion
• Escalating use of pressors or MCS to maintain SBP and end-organ perfusion 1

Stage E: Extremis

• Cardiac arrest
• Refractory hypotension and hypoperfusion
• CPR
• SBP only with resuscitation
• PEA or recurrent VT/VF 1

Practical Diagnostic Approach

1. Initial Assessment:

   • Evaluate for hypotension and signs of hypoperfusion
   • Check lactate levels and other markers of end-organ dysfunction
   • Perform ECG to identify acute myocardial infarction or arrhythmias 1, 2

2. Echocardiography:

   • Perform immediate echocardiography to assess:
     • Ventricular function
     • Mechanical complications
     • Valvular disease
     • Shock phenotype (LV, RV, or biventricular failure) 2

3. Invasive Hemodynamic Assessment:

   • Consider pulmonary artery catheterization for patients with:
     • Progressive hypotension unresponsive to initial therapy
     • Unclear shock etiology
     • Need for tailored therapy based on shock phenotype 1, 2

Common Pitfalls and Caveats

• Pre-shock Misdiagnosis: Patients with compensatory vasoconstriction may maintain near-normal systolic blood pressure despite malperfusion, which can be falsely reassuring. These normotensive but hypoperfused patients represent a high-risk cohort with lower average cardiac output and high mortality (43% in-hospital) 1

• Overlapping Shock States: Cardiogenic shock may coexist with other shock states (e.g., septic shock), making diagnosis challenging. A thorough evaluation including clinical, laboratory, and echocardiographic assessment is essential 3

• Delayed Recognition: Failure to recognize early signs of cardiogenic shock can lead to delayed intervention and worse outcomes. Early recognition and prompt intervention are critical for improving survival 1, 2

• Phenotype Identification: Failure to identify the specific shock phenotype (LV, RV, or biventricular) may lead to inappropriate therapy selection. Tailoring treatment to the specific phenotype is essential for optimal outcomes 1, 2

By systematically evaluating both clinical and hemodynamic parameters and applying the SCAI classification system, clinicians can accurately diagnose cardiogenic shock and determine its severity, which is crucial for guiding appropriate therapeutic interventions and improving patient outcomes.